Composite construction for distributor components



March 9, 1965 w. MCCANDLESS 3,172,967

COMPOSITE CONSTRUCTION FOR DISTRIBUTOR COMPONENTS Filed Nov. 13, 1962 2Sheets-Sheet l INVENTOR. VV\LLIAM M QANDLEfiS:

A'T'TO RN EYS March 9, 1965 w. MOCANDLESS 3,172,967

COMPOSITE CONSTRUCTION FOR DISTRIBUTOR COMPONENTS Filed NOV. 13, 1962 2Sheets-Sheet 2 INVENTOR. W1 LLIAM M- C/Awmmss s ATTORNEYS United StatesPatent 3,172,967 COMPDSITE CUNSTRUCTION FQR DISTRTBUTOR tIOMIONENTSWilliam McCandless, Toledo, Ohio, assignor to John Erlller Industries,Inc., Toledo, Ohio, a corporation of Filed Nov. 13, 1962, Ser. No.237,269 Claims. (Cl. ZOO-19) This invention relates to a distributor andmore par ticularly to details of construction of a cam, points, androtor of a distributor.

Distributors have remained substantially unchanged for the last twentyto thirty years, probably because they have been relativelysatisfactory, being reasonably reliable, producing satisfactory results,and not requiring excessive maintenance. There are, however, severalaspects of distributors as presently known, upon which improvements canbe made. For one thing, distributors presently are quite expensive andespecially so when it is considered that a one cent to two cent savingsin the overall cost of an automobile is considered of the utmostimportance to automobile manufacturers. Distributors also tend to besomewhat sluggish at times during rapid acceleration or deceleration,due to the inertia of some of the comparatively heavy rotating partstherein.

The present invention relates to a new distributor construction whichachieves several advantages, a principal one of which is a substantialreduction in the cost of the distributor. The new distributorconstruction also achieves a substantial reduction in weight and thusenables the distributor to be more responsive to sudden changes in speedand thereby achieve better engine performance.

A distributor according to the principles of the present inventionembodies a circuit breaker cam made of a nonmetallic, plastic materialwhich is functionally integral with a bushing which constitutes a sleevebearing for the cam. The cam also has an extension above it whichdirectly supports a rotor of the distributor. The new distributor alsois characterized by a breaker arm having a metal cam follower ratherthan the usual plastic or fiber one heretofore employed. The plasticcircuit breaker cam and related parts, along with the simplified designof the cam and rotor, reduces the weight of these parts to approximatelyone-sixth of the weight of the corresponding components of conventionaldistributors as now known in the art. This weight reduction improvesengine performance by reducing the sluggishness or lag heretoforeinherent in distributor operation due to the weight of the rotatingparts. The reduction in weight of these parts also enables smaller andlighter governor weights to be used which again increases the responseof the distributor.

Of more importance perhaps, is the substantial cost reduction broughtabout by the new construction. The onepiece construction of the cam androtor extension reduces the number of parts in the distributor andthereby reduces assembly time. Because a plastic extension is used toconnect the cam and rotor, the rotor itself can be of simplerconstruction, not requiring the usual heavy plastic rotor supportheretofore needed to achieve proper insulation between the contact armof the rotor and the metal shaft supporting it. This further reducesmanufacturing cost and weight. Because the governor weights can besmaller and lighter, they can be blanked from metal stock, such as /8inch metal stock for many distributors, which further reduces themanufacturing costs of the weights. These weights at the present aresufiiciently thick that they usually are made by a sintering techniquewhich is the least expensive way of producing them in most instances.Because the governor weights are lighter, the springs holding them intheir inner positions 3,172,967 Patented Mar. 9, 1965 also can besmaller and less expensive. As a combined result, the cost of thedistributor can be reduced about fifty to seventy cents.

The molded plastic cam has an additional advantage in that its shape isnot limited as has been heretofore necessary with metal cams which mustbe ground, with the final shape thereof being subject to the limitationsof the grinding operation. Further, with theplastic cam and metalfollower combination, less wear is encountered on all components. Thecam normally is subject to less wear than the follower because the camhas a number of high points or lobes which wear whereas the follower hasonly one wear point. For a six cylinder engine, the follower receivessix times the wear of the cam because the follower engages six lobesduring one revolution of the cam whereas each lobe only engages thefollower once during each revolution. Thus, the use of the metalfollower and plastic cam places the wear resistance where it should be.

It is, therefore, a principal object of the invention to provide animproved distributor having the advantages outlined and discussed above.

Other objects and advantages of the invention will be apparent from thefollowing detailed description of a pre ferred embodiment thereof,reference being made to the accompanying drawing, in which:

FIG. 1 is a view in vertical cross section of a distributor embodyingthe principles of the invention, with breaker points and a rotor thereofbeing offset from their normal positions for purposes of illustration;

FIG. 2 is a view in cross section taken along line 22 of FIG. 1 andshowing in particular a circuit breaker cam and breaker contact pointsembodying the invention;

FIG. 3 is a horizontal view in cross section taken along the line 33 ofFIG. 1 and showing the rotor construction of the new distributor;

FIG. 4 is a view in horizontal cross section taken along the line 44 ofFIG. 1 and showing the construction of the governor weights of thedistributor, and

FIG. 5 is a view in perspective of the rotor design.

Referring to the drawing, and more particularly to FIG. 1, a distributorindicated at 10 functions substantially the same as most conventionaldistributors now known in the art. It can be divided into severalassemblies, including a circuit breaker assembly indicated at 12, agovernor assembly indicated at 14, and a rotor assembly indicated at 16.Each assembly operates in the same manner as the corresponding assemblyof a conventional distributor.

Referring to the circuit breaker assembly 14, a timer shaft 18 extendsupwardly through a lower metal housing 20 of the distributor It with thetimer shaft 18 being driven through a gear 22 in the usual manner tocause the shaft to rotate in a fixed relationship with respect to theengine crankshaft. In this instance, the timer shaft 18 includes anupper spindle or axle 24 upon which a circuit breaker cam 26 rotates.The cam 26 actually consists of two parts, an outer sheath 28 formingthe contour of the cam with the usual dwell portions 30 and lobes 32(FIG. 2), and a metal inner bushing 34 fixedly mounted therein,preferably at the time the cam member 26 is molded. The bushing 34preferably has a knurled outer surface to provide secure engagement withthe sheath 28 which is of plastic, for example, nylon or Delrin. Thecombination metal and plastic construction of the cam 26 is preferred toa cam made entirely of plastic because closer dimensional tolerances canbe attained with the combination than with a solid plastic cam whichtends to shrink non-uniformly.

It will be noted that the steel bushing 34 constitutes at least half thethickness of the overall cam wall with the sheath 28 making up theremaining portion.

Around the cam 26 is a horizontal partition or base plate 36 upon whichis pivotally mounted a circuit breaker plate 38 which carries a circuitbreaker arm 40 supported on the plate 38 by a pivot pin 42. The circuitbreaker arm 40 includes a circuit breaker contact or point 44 which isconnected to a metal strip 46 which also forms a metal cam follower 48.In this instance, the metal strip 46 also is bent around and behind thearm 40 to act as a return spring for the arm and to provide electricalcontact with a terminal t} which is suitably connected to the usualprimary winding of the ignition coil. The metal strip 46 is backed up bya plastic breaker arm body 52 which is mounted on the pivot pin 42 andinsulates the strip 46 from the pin 42 and the plate 36. The metal camfollower 48 can also be formed in other ways, as by being a separatepiece attached directly to the body 52.

The contact 44 makes and breaks with a stationary contact 54 in theusual manner as the breaker arm 4t: moves back and forth due to theengagement of the metal follower 48 with the plastic cam sheath 28. Thismakes and breaks the circuit through the primary winding and in turninduces a large voltage in the secondary winding. The secondary coil isconnected to a central terminal or socket 56 in an upper insulatinghousing 57 of the distributor. The central terminal 56, in turn, iselectricaily connected through a rotor indicated at 6%? of the rotorsection 16 to individual peripheral terminals 58, each of which isconnected to a hot terminal of a spark plug. The circuit breakerassembly 14 induces the high voltage and the rotor assembly 16 directsthis voltage to a particular spark plug.

The rotor 60 in this instance simply comprises a metal strip forming aresilient contact arm 62 and an outer conducting arm 64 with a contactpoint 66. The arm is attached directly to an upper end of a camextension 68 which is structurally integral with the cam sheath 2% andextends concentrically upwardly therefrom. The rotor 60 can bedetachably mounted on ears 70 of the extension 68 to facilitate assemblyof the distributor components.

The rotor 60 carries a high voltage and therefore must be well insulatedfrom any metal parts other than the terminal sockets 5t? and 58. In theusual distributor which has a metal shaft extending up to a point closeto the rotor, insulation must be provided by a heavy insulating armconstituting part of the rotor and upon which the metal conducting stripis mounted. Because there is no metal in the present distributor closerthan the bushing 34, the entire insulating arm can be dispensed with andthe connecting strip constituting the rotor 69 merely mounted on theupper end of the extension 68, which is a substantial factor in reducingthe overall weight as well as the cost of the distributor.

The governor section 14- advances the spark or the point at which thecontacts 44 and 54- make and break by rotating the cam 26 slightlyfurther in the direction of rotation when the speed of the engineincreases. The governor section 14 includes two weigats 72 which arepivotally mounted by pins 74 on a governor plate '76 which is afiixed tothe shaft 18 and rotates therewith. The free ends of the weights 72 areconnected to springs 78 which in turn are connected to projections 8tforming part of the plate '76. The springs 78 restrain the weights fromoutward movement until the shaft reaches a predetermined speed. Theweights 72 have the usual pins 82 projecting upwardly therefrom whichextend into slots 84 of a governor arm 86, with the pins causingrotation of the arm 86 as they swing outwardly. The arm 86 in thisinstance is structurally integral with the cam sheath 28 and causes thecam 26 to rotate slightly in a clockwise direction on the axle 24 as theweights swing outwardly.

Because of the lighter weight of the rotating components of thedistributor, the governor weights can be El much thinner than heretoforeand can be blanked from 42 inch stock for many distributors, in place ofthe usual comparatively expensive sintering operation which constitutesthe least expensive way of making the weights in most instances instandard distributors.

A vacuum attachment (not shown) is mounted on the lower housing 20 andhas an arm (not shown) connected to the breaker arm plate 38 to causethe plate 38 to move relative to the base plate 36 and also relative tothe cam 2a. This retards the spark during acceleration and is the sameas those vacuum units employed in standard distributors. Eence, and forclarity of illustration, it is not shown at all in the drawings and willnot be discussed further in the specification.

From the above, it will be seen that the distributor 10 basicallyfunctions the same as any conventional distributor with the circuitbreaker section 12 making and breaking the circuit to a primary windingof a coil in order to produce high voltage for a spark plug, theparticular spark plug being controlled by the rotor section 16. Thegovernor section 14 also operates in the usual mannor to advance sparkduring increased engine speed and the vacuum unit (not shown) isemployed to retard the spark during periods of acceleration and thelike.

Otherwise, the distributor it is substantially different fromconventional distributors. The combination plastic sheath 2.3 and metalbushing 34 enable the cam 26 to have closely held dimensional tolerancesand yet reduce the Weight of the cam, particularly the outer portionthereof where the inertia is the greatest. The plastic extension 68which is integral with the sheath 25 also is much lighter than the usualmetal shaft heretofore used and extending through the cam, and furtherprovides savings by simplifying the construction of the rotor 60. Theusual heavy insulating rotor arm is completely eliminated, as previouslypointed out, which reduces production costs and further reduces weight.The governor weights 72 can be thinner and less expensive, because ofthe lesser weight and inertia of the other rotating components. All ofthese features contribute to a lighter distributor which achievesimproved performance and is substantially less expensive than thoseheretofore known. The shape of the plastic cam also no longer need beunduly restricted to the extent heretofore necessary when the cam wasmade of metal and was ground. Further, by employing the plastic cam andthe metal follower point, the problem of wear is substantially reduced.

Various modifications of the above described embodi-- ment of theinvention will be apparent to those skilled in the art and it is to beunderstood that such modifications can be made without departing fromthe scope of the invention, if they are within the spirit and tenor ofthe accompanying claims.

I claim:

1. In a distributor including a housing, a timer shaft extending intosaid housing, a circuit breaker cam rotatably mounted on said shaft, acircuit breaker arm adjacent said cam and having a follower engagingsaid cam to cause pivotal movement of said arm, a rotor above said camand rotatable therewith, and a governor assembly controlling theposition of said cam, the improvement comprising said circuit breakercam including a metal bushing supported on a portion of said shaft forrotatable movement with respect thereto, and a plastic sheath aroundsaid bushing and functionally integral therewith, said bushing being atleast as thick as said plastic sheath so as to constitute at least halfthe thickness of the overall cam wall, said plastic sheath forming theouter surface of the cam.

2. In a distributor including a housing, a timer shaft extending intosaid housing, a circuit breaker cam rotatably mounted on said shaft, acircuit breaker arm adjacent said cam and having a follower engagingsaid cam to cause pivotal movement 'of said arm, a rotor above said camand rotatable therewith, and a governor assembly controlling theposition of said cam, the improvement comprising the other surface andnot more than half the thickness of the wall of said circuit breaker cambeing of a plastic material, the remaining thickness of said wallconstituting a metal bushing on said shaft, the height of said bushingnot exceeding the height of said cam and the follower of said circuitbreaker arm being of metal.

3. In a distributor including a housing, a timer shaft extending intosaid housing, a circuit breaker cam rotatably mounted on said shaft, acircuit breaker arm adjacent said cam and having a "follower engagingsaid cam to cause pivotal movement of said arm, a rotor above said camand rotatable therewith, and a governor assembly controlling theposition of said earn, the improvement comprising said circuit breakercam including a metal bushing rotatably supporting said cam on saidshaft and a plastic sheath functionally integral with said bushing andforming a plastic cam surface, a plastic extension extending upwardlyfrom said plastic earn sheath, and said rotor being attached directly tothe upper end of said extension.

4. In a distributor including a housing, a timer shaft extending intosaid housing, a circuit breaker cam rotatably mounted on said shaft, acircuit breaker arm adjacent said cam and having a follower engagingsaid cam to cause pivotal movement of said arm, a rotor above said camand rotatable therewith, and a governor assembly controlling theposition of said cam, the improve- U3 ment comprising said cam having aplastic sheath forming a plastic cam surface, a plastic extensionextending upwardly from said cam sheath, and said rotor being attacheddirectly to the upper end of said extension and consisting essentiallyof an elongate strip of electrically conducting material.

5. In a distributor including a housing, a timer shaft extending intosaid housing, a circuit breaker cam rctatably mounted on said shaft, acircuit breaker arm adjacent said cam and having a follower engagingsaid cam to cause pivotal movement of said arm, a rotor above said camand rotatable therewith, and a governor assembly controlling theposition of said cam, the improvement comprising said cam including ametal bushing supported on said shaft for rotatable movement, and aplastic sheath functionally integral with said bushing and forming anouter cam surface, said breaker arm having a metal follower for engagingsaid plastic cam surface, a plastic extension extending upwardly fromsaid cam sheath, and said rotor comprising an elongateelectrically-conducting member removably attached directly to the upperend of said extension.

References Cited in the file of this patent UNETED STATES PATENTS1,121,996 Gassmann Dec. 22, 1914 1,507,493 Lealre Sept. 2, 19241,886,566 Mallory Nov. 8, 1932 2,688,055 Schneider et a1. Au 21, 1954

1. IN A DISTRIBUTOR INCLUDING A HOUSING, A TIMER SHAFT EXTENDING INTOSAID HOUSING, A CIRCUIT BREAKER CAM ROTATABLY MOUNTED ON SAID SHAFT, ACIRCUIT BREAKER ARM ADJACENT SAID CAM AND HAVING A FOLLOWER ENGAGINGSAID CAM TO CAUSE PIVOTAL MOVEMENT OF SAID ARM, A ROTOR ABOVE SAID CAMAND ROTATABLE THEREWITH, AND A GOVERNOR ASSEMBLY CONTROLLING THEPOSITION OF SAID CAM, THE IMPROVEMENT COMPRISING SAID CIRCUIT BREAKERCAM INCLUDING A METAL BUSHING SUPPORTED ON A PORTION OF SAID SHAFT FORROTATABLE MOVEMENT WITH RESPECT THEREOF, AND A PLASTIC SHEATH AROUNDSAID BUSHING AND FUNCTIONALLY INTEGRAL THEREWITH, SAID BUSHING BEING ATLEAST AS THICK AS SAID PLASTIC SHEATH SO AS TO CONSTITUTE AT LEAST HALFTHE THICKNESS OF THE OVERALL CAM WALL, SAID PLASTIC SHEATH FORMING THEOUTER SURFACE OF THE CAM.